Dietary sodium intake independently increases mortality in end-stage renal disease (ESRD). The benefits of sodium restriction in patients undergoing hemodialysis (HD) are consistently demonstrated in scientific reports, though little is known about the appropriate prescription of dietary sodium intake. Specifically, there is a lack of evidence of either harm or benefit of universal practiced recommendations. The overall objective of the proposed NINR Career Development Award is to receive advanced research training in: (1) Renal physiology including fluid and electrolyte balance, the physiology and mechanics of HD therapy and body composition; and the role of nutrition in management of ESRD; (2) Symptom science in patients with ESRD, the scientific rationale for symptom management, and how symptoms are related to physiological and nutritional changes; (3) Methods and measurement strategies of renal-related physiological variables, biological markers, and patient symptoms; (4) Repeated measures, longitudinal data analysis of physiologic variables; (5) Bioethics of studying vulnerable populations with chronic illness and how that content relates to the responsible conduct of research (RCR), and data/safety monitoring and randomized controlled trials (RCT). As part of my career development, I will conduct an RCT to study the effects of three levels of sodium intake (ambient control group [CG], 1500 mg/d [1.5G], 2400 mg/d [2.4G]) on the HD symptom profile of ESRD patients. The proposed study will be the first of its kind to offer empiric support for or against the current dietary sodium intake recommendations. The study will provide the first step to gathering essential evidence needed to correctly identify the appropriate dietary sodium restriction prescription. The specific aims are to: 1) demonstrate that symptom profiles and interdialytic weight gain (IDWG) vary among three sodium intake groups (CG, sodium intake of 1.5G, sodium intake of 2.4G), controlling for age, race, gender, and duration of disease; 2) demonstrate that the effect of HD-specific variables [ultrafiltration rate (liters/hour) and total luid removed (liters)] on the symptom profiles vary among the three sodium intake groups (CG, 1.5G, 2.4G), controlling for age, race, gender, and duration of disease; 3) determine whether total body water (TBW), extracellular fluid (ECF), and intracellular (ICF) measured with bioimpedance spectroscopy (BIS) varies across sodium intake groups (CG, 1.5G, 2.4G), controlling for age, race, gender, and duration of disease. Forty-two adult participants will be recruited from the Hospital of the University of Pennsylvania Renal, Electrolyte, and Hypertension Division (Renal Group) and will be randomized to one three sodium-controlled diets during a 5- day stay in the Clinical and Translational Research Center. The primary study outcomes are IDWG and symptom burden as measured with the Palliative Care Outcome Scale-Renal. Secondary outcomes include TBW, ECF, ICF, and HD-specific variables. A series of multiple regression models will be used to test the study aims.